Method of modifying color in vacuum tube lights



Oct. 13, 1-931. 6. CLAUDE ET AL 1,827,705

METHOD OF MODIFYING COLOR IN VACUUM TUBE LIGHTS Filed OCC. 15, 1927 a] true 41 to z GEORGE 5 CLAUDE JEAN ME de' BEAUFORT 5 1 M] l few/nu W cntv.

Patented Oct. 13, 1931 UNITED STATES PATENT OFFICE GEORGES CLAUDE AND JEAN E. DE BEAUFORT, OF BOULOGNE-SUR-SEINE, FRANCE,

.: ASSIGNORS '10 CLAUDE NEON LIGHTS, INQ, OF NEW YORK, N. Y.,

or new Yon]:

A. CORPORATION METHOD OF MODIFYING COLOR IN VACUUM TUBE LIGHTS Application filed October 15, 1927, Serial No. 226,502, and in France October 18, 1926.

This invention relates to lighting systems, such, for example, as that comprising the well known neon lights, in which the passage of a high potential alternating current through a column of more or less rarefied gas,

such as neon, causes the tube contents to glow and radiate light.

Up to the present time,

so far as is known, 1t has not been ossible to modify the color of light emitted y a gas or a vapor enclosed .own color, that is, the same color as if it were alone contained within the tube. For example,1f neon'gas and a mercury vapor are contained within a tube either the neon gas alone will commence to vibrate or the mercury vapor alone will commence to vibrate depending upon' conditions, but it has. heretofore been found impossible in a given ortion of the tube, to obtain a mixture'of light from both the neon gas and the mercury va or which will afford a color applicable to lig tin i momentary modification of the li ht emitted from a seous mixture enclose in a luminescent tu c has been produced by abruptly varying the current passing through the tube, but this has obviously not resulted in a permanent maintenance of the modified color.

The present invention has for one of its objects to obtain a modification of the color of the light emitted by a' tube of rarefied gas and maintain that modified color permanently or for a predetermined period ot time. To this end, we have discovered that the color of such a tube may be varied or modified and the modified color maintained constant by changing the frequency of the-alternating current passing through the tube. Accordingly, the tube instead of being operated on I alternating current at that frequency, say 60 cycles, usually obtained tro n'an industrial supply, as is now the practlce to obtain its current.

the usual industrial supply by means of a transformer. The tube may also contain mixtures of gases and/or vapors with the same result, such for example as a mixture of neon gas and mercury. To obtain the desired modification of color suitable devices are included in the circuit with the transformer and the tube to produce an oscillation The lighting system described will afford a variation in the color of the light usually emitted from a vacuum tube and maintain that color constant, under unchanging conditions.

It is also an object of the invention to permit a selection, as desired, of the altered color or the usual color emitted by the gas or the mixtlft'e in the tube. With this end in view provision is made for selectively connecting the lamp with either the oscillating circuit hereinbe'fore described or with a source of high potential non-oscillatin current.

vThese and other objects 0 the inventlon and the means for their attainment will be more apparent from the following detailed description of an embodiment thereof taken in connection with the accompanying drawing, illustrating, conventionally, a rarefied gas tube, adapted for selective connectlon with either an oscillating circuit or a nonoscillating circuit.

In the lighting system as illustrated the tubular envelope 6 of the tube light containing a rarefied gas, such as neon, or helium or the like alone or mixtures of such gasesor a metallic vapor, such as mercury vapor, or

say 5000 cycles to a mixtureoi such a gas with a vapor, such ing through a press 11. The tube 6 is connected by the leads 9 and 10 with the terminals 14 and 12 of a circuit selecting device, such as a double pole switch 13, by which an electrical connection may be selectively made with either a source of oscillating current or a source of non-oscillating current. Obvious- 1y this selection of circuits may be made manually by means of the switch 13 as shown, or mechanically, as by, say, a timed rotary switch or the equivalent, by which the respective circuits may be thrown in periodically in predetermined manner. 1

A source of low potential alternating curs rent is indicated at G connected with main conductors 15 .and 16 which may represent the usual industrial, alternatin non-oscillating current supply at say a equency of 60 cycles.

- To operate the tube 6 for the purpose of obtainin the usual or characteristic hght emitted y the tube contents, these malns 15 and 16 are respectively connected by the leads 17 and 18 with the terminals of the primary coil 20 of the transformer 21. The secondary coil 22 of the transformer 21 is connected with the contacts 1 and 3 by the'wires 23 and 24 50 that the tube 6 may be electrically connected with the transformer 21 and operated from the commercial supply mains 15 and 16 at the requisite high potential, but at normal frequency, in a manner well understood, to give the characteristic color of the tube contents.

The transformer 21 may take any form suitable to the situation, that is, it may be a leak transformer in order that it may compensate for the negative resistance of the ube or if an ordinary commercial transformer is used, a reactance or other current controlling device (not-shown) may be included in the circuit for the same purpose, as will be understood. a

For the operation of the tube 6 at hi quency, in the attainment of a modi cation of the color emitted b the tube contents, the switch 13 is availed o to disconnect the tube from the non-oscillatingcircuit described and to connect the tube 6 with an oscillating circuit, such as will now be described.

Connected with the source of commercial instrumentahty of the transformer 21, the

current, i. e. the mains 15 and 16, is the transformer 26 whereof the primary coil 27 is connected, as by leads 28 and 29, with the mains 15 and 16, respectively, and whereof the secondary coil 30 is'included in the oscillatinglcircuit through the wires 31, 32 leading to t e contacts 2 and 4. I

As has been pointed out" hereinbefore, the color of light emitted from the tube 6 may be modified and the modification maintained permanently or for any desired period of time by altering the frequency'of the electric current passin through the tube.

The color 0 tained from a pure gas enclosed in a luminescent tube, electrically excited depends upon the number of the rays in the spectrum, on the position'of the rays in the spectrum and on the com arative intensity of the rays. The number 0 the rays and their position in the spectrum do not change, whatever may be the processutilized to produce the spectrum, and this constitutes a constant characteristic of the gas. The comparative intensity of the rays may be affected, however. It is on the comparative intensity of the rays that the color of the light depends and it is by affecting this condition that the modification of the light in accordance with this invention is obtained.

For example a tube filled with ure neon emits a red orange light at a low requencv, say 60 cycles, whereas at a high frequency it will emit a yellow orange light. At low frequency, the red rays are the more intense whereas at ahigh frequency the green rays are the more intense. This is a common characteristic of such gases. For instance, helium, excited at low frequency, emits a pinkish yellow light whereas at high frequency the light is more of a violet color. At low frequency the red and yellow'rays predominate whereas, at high frequency, the violet rays predominate. With a mixture of a gas, say neon, and a vapor, say mercury vapor, in a luminescent tube, the mercury vapor vibrates alone at low frequency and the tube,emits a blue light. If the excitation is effected at high frequency the neon vibrates at the same t1me as the mercury and there may be observed in the spectrum the simultaneous presence 'of the spectrum-of neon and the spectrum of mercury and this is stable. The light emitted by the tube is neitherthe blue of the mercury nor the reddish color of the neon gas but is a mixture of the two and is of a pinkish color. With a mixture of helium and mercury vaor, at low frequency, the tube emits a green- 1 f ish light while at high frequency the tube emits a yellowish light. Referring again to the drawing, instead of operating the-tube on high potential alternating current at a frequency say of 60 cycles, which is that usually obtained from an industrial 'suppl and which would be the case when the tu e 6 is operated through the tube may be operated at a much higher fresay 5000 cycles, when operated from .120

bviously any type of frequency ing sustained oscillations of a definite and substantially constant frequency, the efi'ect upon a mixture of gases and/or vapors, e. g.

mixture of neon and mercury, is constant, that is to say, the neon and mercury are caused to simultaneously emit light and the composition of the spectrum of the composite light is substantially uniform and constant. In the illustrated embodiment a spark gap formed by the terminals 37, 38 is shown connected between one terminal of the secondary coil and the switch terminal 2 and a condenser 33 is connected in parallel with the secondary coil 30 by the wires 34, 35, as will be understood, for the purpose of accumulating a charge sufiicient to break down the gap. Of course the gap, condenser and coils are to be designed so that the condenser will carry a Very large charge before. the gap is broken down in order that the desired high frequency may be obtained, the relative proportions not being required to be here given as these will be found within the ability of an expert in the art.

It will thus be seen that by the power circuit described and by properly proportioning the constants of the circuit, the comparative intensity of the rays of the .spectrum of a single gas contained within the tube may be modified and thus the color of the light therein produced, modified. The invention is equally applicable where a single gas is contained within the tube as where a mixture of gases and metallic vapors are contained within the tube, such as for instance, neon gas and mercury vapor, and the spectrum of the components is obtained in a permanent and stable manner. In the latter case the light emitted is a mixture of the colors which are characteristic of each component.

These two phenomena are obtained by the same process which consists in feeding the tube by current at high frequency, say 5000 cycles, instead of feeding it at the ordinary low frequency.

In utilizing this process it is possible to obtain changes of color in the same tube, which can be prolonged at will and can be used for luminous advertising. For example,.a tube containing a mixture of neon and mercury may be alternately fed, first with the alternating current at low frequency in the usual way as indicated by the circuit including the transformer 21 to cause the tube to radiate light of the known blue color or it may be supplied as desired with a high frequency current, as by the circuit including the transformer 26 and the tube will instantly light up with an intense pink color which may be maintained as long as desired. Furthermore, the intervals of time between operat-, ing the tube at low frequency and high frequency may also be prolonged as desired, which difierentiates the process from those prior lmown experiments in which a temporary instantaneous change in color is obtained by varying the current.

Various substitutions may be made for the component elements of the circuits by which the invention is shown as being realized. Furthermore the invention is not to be deemed limited to a combination including both an oscillatory circuit and a non-oscillatory circuit but the inclusion of the non-oscillatory circuit is to be deemed permissive and has been illustrated in order to show the widest usefulness of the invention.

What we claim is:

1. A lighting system comprising a tube of rarefied gas, two sources of high potential alternating current, electrical connections between said sources and the'tube, a frequency changer included in the circuit of one of the sources and means to selectively connect either of the two sources to the tube.

2. A lighting system including a tube of rarefied neon in combination with two circuits, one at low frequency and the other at high frequency and means to selectively connect the tube with one of the circuits to vary the color of the light emitted by the tube.

3. The method of operating a rarefied gas tube comprising alternately impressing upon the tube discharge currents of different frequencies.

4%. The method of modifying the color of light emitted from a rarefied gas tube contaming neon gas and mercurycomprising intermittent-ly increasing the frequency of the alternating current feeding the tube from low frequency to approximately 5000 cycles.

5. The method of operating a rarefied gas tube comprising selectively operating the tube with a current of low frequency and with a current of high frequency.

6. The method of operating a rarefied gas tube comprising selectively operating the tube with a current of a frequency of cycles and with a current of a frequency of 5000 cycles.

7. A lighting system for luminescent tube tube comprising a luminescent tube having internal electrodes, a source of low potential low frequency current, two step-up transformers, means to connect the electrodes with either of the transformers, and frequency-increasing means connected to one of the transformers.

8. The method of obtaining a light from a mixture of substances in the vapor phase contained in a sealed envelope, at least one of which substances does not, at low frequencies, emit light in the presence of the other compo; nents, which comprises impressing upon the envelope contents, in the absence of a low frequency discharge, an electrical discharge characterized by sustained high frequency oscillations, the frequency of which is predetermined, definite. and substantially uniform, which dischargesimultaneously ionizes the 4: estates particles of all of the said substances. and causes 'each substance simultaneously to emit light of apredetermined and substantially constant and uniform color, the light emitted by each constituent cooperating and blending with the light simultaneously emitted by the other constituents thereby roducing a composite light of a redetermmed and substantially constant co orcomprising wavelengths of all the components of said mixture.

9. The method of obtaining a light from a mixture of substances in the vapor phase contained in a sealed envelope containin internal electrodes, at least one of which su stances,

does not, at low frequencies, emit light in the presence of the other components, which comrises impressing upon the envelope contents, in the absence of a low frequency discharge, an electrical discharge directly communi-. cated to said mixture of substances from said internal electrodes and characterized by sustained high frequency oscillations, the frequency of which is predetermined, definite and substantially uniform, which discharge 5 simultaneously ionizes the particles of all of the said substances and causes each substancesimultaneously to emit light of a predetermined and substantially constant and uni- -form color, the light emitted by each constituent cooperating and blending with the light simultaneously emitted by the other constituents thereby producing a composite light of a predetermined and substantially constant color comprising wave lengths of all the components of said mixture.

' In testimony whereof we aflix our signatures.

GEORGES CLAUDE. v JEAN M. E. on BEAUFORT, 1 

